A control device for an electric vehicle, which includes temperature detecting means for detecting temperatures of individual power devices and outputting respective temperature values thereof and a gate control circuit having a protective function for limiting a current of an inverter on the basis of the highest device temperature among the temperature values output by the temperature detecting means, has been proposed as a conventional device for protecting an inverter element from overheating (see PTL 1, for example).
Further, in a proposed overheating protection method, switching characteristics of a switching element provided in an inverter, such as normally ON loss, switching loss, and transient thermal impedance, are stored together with a switching element loss calculation formula in a storage device serving as a memory of a control unit, whereupon a CPU of the control unit derives a loss of the switching element from the calculation formula, the normally ON loss, switching loss, and so on stored in the memory having been inserted into the calculation formula using as variables an output current approximating a rectangular wave, a control factor, and an output frequency that are detected in the inverter. The CPU then calculates an element junction temperature using the derived loss and the transient thermal impedance of the memory, and implements output current control on the inverter such that the element junction temperature does not exceed a set temperature (see PTL 2, for example).